Why does Ecclesiastical Latin pronounce "au" as written?

Question

Salvete,

Ecclesiastical Latin, by which I mean here the Italian Traditional Pronunciation seems to have preserved some characteristics of rustic Roman pronunciation despite the spelling remaining unchanged:

ae - e (attested B.C.) oe - e (not sure when) ti - tsi (5th Century A.D.?)

I believe [v] (or at least [β]) and palatalised 'c' are attested quite early too. The pronunciation of 'm' and 'n' as full consonants could be put down to influence of the spelling, but from what I have read, 'au' was pronounced [o:] at a very early date. So my question is, if Italian Ecclesiastical Latin has preserved the rustic pronunciations of 'ae' and 'oe' without changing the spelling, why is 'au' not pronounced [o:]? Conversely, if 'au' is pronounced as written, why isn't 'ae' or 'oe'?

Ago vobis gratias Valete

Answer 1

I think I may have an answer to my own question.

Adams in "Social Variation and the Latin Language" says that there were two independent developments - 'au' was pronounced 'o' in certain rustic Latin words during the Classical period but in general 'au' remained the pronunciation, then there was a later development where words from Latin containing 'au' changed to 'o' in various, but not all Romance languages.

"Hence it is not correct to say ... that It. oro (CL aurum) shows the Vulgar Latin form, since the Italian reflex has an open o. It is true that a 'rustic' form orum for aurum is attested in Latin ... but the o of that form would have differed in quality (being close) from that of (e.g.) the Italian word. The Latin form orum and the Italian oro derive from independent monophthongisations."

It seems that 'au' survived longer in Latin than other diphthongs and the rustic form did not oust the standard form. Adams mentions that it survived in Romanian and other Romance dialects, and Portuguese shows a diphthong ('pouco' etc.) that also represents a vestige of this.

So, it would seem that the traditional Italian pronunciation of 'au' is in line with the historical development of Latin. Adams also mentions that 'au' is not generally written as 'o' in error, unlike 'ae' which is often written as 'e'.

He adds: "But since the o-spelling is so tied to particular lexical items it would not do to suggest that in rural Latin a general monophthongisation had occurred."